Inductively powered illumination system for tubular fabric

ABSTRACT

An illumination system for tubular fabric of indeterminate length such as knitted tubular fabric produced by a circular knit textile machine which includes a light source supported in a floating manner inside continuously advancing tubular fabric together with a receiving antenna connected thereto and a transmitter having a transmitting antenna outside the fabric by means of which a beam of high radio frequency energy is transmitted through the fabric to the receiving antenna for energizing the light source and thereby providing illumination behind the wall of the fabric to facilitate visual observation of the advancing fabric for the detection of imperfections and the like.

United States Patent [1 1 Grover [111 3,806,940 [451 Apr. 23, 1974 INDUCTIVELY POWERED ILLUMINATION SYSTEM FOR TUBULAR FABRIC William B. Grover, Rt. 8, Box 572, Sumter, SC. 29150 Filed: Apr. 20, 1973 Appl. No.: 352,954

References Cited 5 UNITED STATES PATENTS l/1963 Baker et al. 315/248 UX Primary ExaminerDonald J. Yusko I Attorney, Agent, or Firm-Townsend M. Belser, Jr.

[5 7] ABSTRACT An illumination system for tubular fabric of indeterminate length such as knitted tubular fabric produced by a circular knit textile machine which includes a light source supported in a floating manner inside continuously advancing tubular fabric together with a receiving antenna connected thereto and a transmitter having a transmitting antenna outside the fabric by means of which a beam of high radio frequency energy is transmitted through the fabric to the receiving antenna for energizing the light source and thereby providing illumination behind the wall of the fabric to facilitate visual observation of the advancing fabric for the detection of imperfections and the like.

10 Claims, 5 Drawing Figures INDUCTIVELY POWERED ILLUMINATION SYSTEM FOR TUBULAR FABRIC BACKGROUND OF INVENTION This invention relates to textile apparatus and more particularly to illuminating means for a tubular fabric inspection frame. In the textile industry and more particularly the knitting industry, the circular knit type of knitting machine is widely used and such a knitting machine produces continuously a tube of knitted fabric. In order to maintain quality standards, as is a common practice with most textile materials, such tubular fabric is generally subjected to an inspection operation for the detection of imperfections in the material such as holes, runs and the like. Upon detection of such imperfections or flaws provisions may then be made for elimination of the inferior material. Since imperfections in such tubular fabric are relatively small, illumination of the material as it advances is necessary for inspection,

but illuminating the outside of the fabric tube does not give the desired degree of illumination for efficient detection of imperfections. Therefore, it has long been recognized that illuminating the tubular fabric from within materially improves the inspection operation. However, inside illumination is beset with problems because the tubular fabric is continuous and a practical and economical means of transmitting electric power from outside a continuously advancing tube to a light source inside the tube has not heretofore been developed. Various solutions to this problem have been proposed such as the use of needle-like contacts which extend through the wall of the tubular fabric and move with the tube as it advances, but the destructive effects on the fabric due to snagging, pulling, etc., have proven unacceptable. It has even been proposed to use photoelectric sensing devices which sense re-flected light from the tubular fabric surface, but these are of an expensive and complicated construction and frequently produce faulty or erroneous readings due to the accumulation of dust, loose fibers and the like.

SUMMARY OF THE INVENTION With the foregoing background of the prior art in mind, a primary object of this invention is to provide a new and novel internal illumination system for tubular fabric.

Another object of this invention is to provide a new and novel illumination system for inspection of tubular fabric of the type produced by circular knit textile machines which permits illumination inside such tubular fabric as it advancescontinuously. A further object of this invention is to provide a new and novel system for illuminating continuously advancing tubular fabric from the inside of the fabric tube so as to materially improve the detection of imperfections and flaws in the fabric.

This invention further contemplates the provision or a new and novel system for internally illuminating a continuously advancing tubular fabric which is simple and inexpensive to build, which permits visual or automated inspection of the fabric to be performed at a high production rate, and which is capable of prolonged operation without breakdown.

Still another object of this invention is to provide a new and novel illumination system for a tubular fabric which permits the application of electrical power to a light source within the fabric without damage to the fabric and the installation and operation of the light source during a fabric inspection operation by relatively unskilled labor with highly accurate results.

Still another object of this invention is to provide an illumination system for tubular fabrics which permits visual inspection of the fabric in a highly efficient manner and which may be easily adapted to a wide range of sizes of such fabrics and to various inspection frame arrangements.

Other objects and advantages of the invention will become apparent from the following description and the annexed drawings.

In general, the object of this invention and other related objects are accomplished by providing an inspection frame through which tubular fabric of indeterminate length is continuously advanced. A transparent or translucent casing is supported by suitable means exteriorly of the fabric in a selected position on the frame and a light source operatively responsive to high radio frequency energy is mounted in the casing together with a radio frequency receiving antenna which is connected to the light source by circuit means. A radio frequency transmitter, including a transmitting antenna,

DESCRIPTION OF DRAWINGS The novel features which are believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its construction and method of operation may be best understood by reference to the specification and the accompanying drawings in which:

FIG. 1 is a side elevational view of the apparatus for inspection of tubular fabric constructed in accordance with the invention;

FIG. 2 is a front elevational view of the apparatus of FIG. 1;

FIG. 3 is a schematic wiring diagram of the electrical circuitry incorporated in the invention;

FIG. 4' is an enlarged elevational view, partially broken away, showing construction details of the light source portion of the apparatus of FIG. 1; and

FIG. 5 is a sectional view taken substantially along line 55 of FlG..4 in the direction of the arrows.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring now to the drawings and to FIG. 1 in particular, an illuminating apparatus is shown constructed in accordance with the invention for use in the inspec- .tion of tubular fabric of indeterminate length of the connected at the upper ends by lateral frame members 13 and 14, respectively, and secured in spaced-apart relationship by lower cross frame members 16 and upper support rods 73 and 74 as shown in FIG. 2.

Means are provided for advancing tubular fabric of indeterminate length, designated generally by the letter T, continuously over and through the frame F. The tubular fabric T may be advanced through the frame F directly from the circular knitting machine. However, in the preferred embodiment, the fabric T is unwound from a supply roll 17 suitably mounted on the frame for unwinding by means of spaced-apart, freely rotatable rollers 18 mounted at their ends in plates 19 secured to the rear side frame members 11 and 12 as shown best in FIG. 1.

The tubular fabric T is arranged to be advanced through the frame F in the direction of the arrow A upwardly from the supply'roll 17 over transversely extending, spaced-apart rollers 22 and 23 supported at their ends in bearing pedestals 24 and 26 respectively secured to the top of lateral frame members 13 and 14.

The tubular fabric T is advanced vertically downward from roller 23 over illuminating means designated generally by the letter L and disposed within the interior of the tubular fabric T as will be explained hereinafter. The illuminating means L is supported on the frame in a floating manner by a pair of horizontally aligned, transversely extending rollers 28 and 29 arranged in parallel, spaced-apart relationship as shown in FIGS. 1 and 5. The rollers 28 and 29 are rotatably mounted at their ends on mounting brackets 31 and 32 which re suitably secured to the front side frame members 11 and 12, respectively, as shown best in FIG. 2. The rollers 28 and 29 are arranged to be driven by a suitable drive means (not shown) and engage the tubular fabric T at their nip for advancing the fabric T through the frame F.

After passing between the rollers 28 and 29, the fabric T moves vertically downward around a third roller 33 rotatably mounted at its ends in bearing pedestals 34 and 36 which are also suitably secured to the front side frame members 11 and 12, respectively, as shown in FIGS. 1 and 2. Roller 33 is also driven by suitable driving means (not shown) in timed relationship with the rollers 28 and 29 so as to wind the tubular fabric T on a mandrel or spindle 37 to form a take-uproll 38 which is rotated by its frictional engagement with the driven roller 33.

The spindle 37 has an annular groove at each end arranged so as to receive and be supported by the inclined upper edges 39a and 41a of forwardly projecting support brackets 39 and 41 which are suitably secured, as by welding or the like, to the inside faces of front side frame members 11 and 12, respectively. As can best be understood by reference to FIG. 1, the inclined edges 39a and 41a maintain the take up roll 38 in frictional driven engagement with the driving roll 33 and, as the fabric T is wound on the spindle 37', the spindle moves outwardly in the direction of the arrow R until the grooved ends of the spindle 37 fall within recesses 39b and 41b near the forward ends of brackets 39 and 41, respectively. When the spindle 37 reaches the recesses 39b and 41b, the take-up roll 38 is full, necessitating its removal and replacement with a fresh spindle 37. FIG. 2 shows the spindle 37 in its outermost position within the recesses.

Referring now to FIG. 3, the system of the invention includes a radio frequency transmitter having a transmitting antenna 77 which is mounted on the frame F in radiation impinging relationship with a receiving antenna 62 mounted within the upper portion of the casing P of the illuminating means L (FIG. 4). The electrical circuitry of the transmitter is shown schematically in FIG. 3 and is preferably housed in an enclosure 81 suitably supported on a lateral cross frame member 83 as shown in FIGS. 1 and 2.

The transmitting antenna 77 is also arranged to be supported on the frame F adjacent to the receiving an tenna 62, and preferably within 6 to 12 inches thereof, by suitable mounting means such as a pair of brackets 84-84, a transverse support rod 86 and an adjustable slide member 86, brackets 84 -84 being secured by welding or the like to the underside of the frame members 13 and 14 as illustrated in FIG. 1.

The transmitter is arranged to be connected to an associated source of electrical power (not shown) by means of conductors 87 and 88 throug an on-off switch 89 as shown in FIG. 3, power supply terminals 90 being provided on enclosure 81 for connection to the power source as will be explained hereinafter. The transmitter includes oscillator circuitry which is connected by means ofa shielded coaxial cable 91 to the transmitting antenna 77.

Referring now specifically to FIG. 3, the oscillator includes an amplifier 92, preferablyv a 61463 vacuum tube, having a heater 93, a cathode 94, a control grid 96, a screen grid 97, a suppressor grid 98 and a plate 99. The cathode 94 and suppressor grid 98 are preferably interconnected as shown.

Referring now to FIGS. 4 and 5, the illuminating means L includes a substantially rectangular support casing formed of rigid transparent or translucent material such as plastic, glass, or the like and designated generally by the letter P. The casing P includes an upper edge 43, a bottom edge 44, and side edges 46 and 47. The casing P is preferably formed so as to include an upper relatively thin portion 48 of substantially planar shape, an intermediate bulbous portion 51 having a pair of spaced apart side walls 51a and 51b defining therebetween an interior chamber 52, and a lower relatively thin depending ridge 49.

In the preferred embodiment, the casing P is constructed by utilizing suitably shaped, half-shell panelsv designated generally in FIG. 5 by the letters S and S" formed from a suitable relatively clear, light transmitting, plastic such as plexiglass. The half-shells S and S" are interconnected in the assembly shown in FIG. 5 by any suitable means such as bolts 53 or the like with plastic spacer-supports 56 and 57 mounted therebetween with outer edges adjacent to the upper and lower edges 43 and 44 of the casing P. A pertinent feature of the invention is that the lower ridge portion 49 of the casing P and the lower edge 44 within the nip of the rollers 28 and 29, with arc'uate portions along the bottom of side walls 510 and-51b conforming generally to the curvature of the adjacent roller peripheries. The casing P is thus maintained in a is accommodated A light source, operatively responsive to radio frequency energy, is mounted on the casing P within the interior chamber 52 between the side walls 51a and 51b. In the illustrated embodiment, the light source comprises a plurality of ionizable, gas-containing tubes 61 arranged in uniform, spaced-apart relationship. Any number of such tubes 61 may be employed depending on the intensity of the light desired. The tubes 61 are preferably of the well-known fluorescent type and 'are suitably supported between the spacer-supports 56 and 57 in vertically extending, parallel, spaced-apart relationship. In the preferred embodiment, the usual tube prongs fit within a series of appropriately spaced apertures drilled into the upper and lower edges of spacersupports 56 and 57, respectively.

A radio frequency receiving antenna 62 is mounted on the casing P and preferably recessed within the upper spacer 57. In the illustrated embodiment, the antenna 62 is of a conventional type comprising a plurality of turns of varnish covered wire, the number of turns being selected in accordance with the resonant frequency to which the antenna is to be tuned. In the preferred embodiment, the antenna consists of nine turns of copper wire layed out flat asa single plane spiral with adjacent wires inches apart.

Also mounted on the casing P are circuit means for conducting the radio frequency energy from the receiving antenna 62 to the light source tubes 61. The circuit means includes at least one strip of conductive material such as copper or the like located in spaced relation, but closely adjacent, to each tube surface, two such strips designated 64 and 65 being provided in the preferred embodiment shown in FIG. 4. The strips 64 and 65 are suspended within the chamber 52 by brackets (not shown) secured to the spacer-support 57, the strips 64 and 65 being electrically connected to the re-' spective ends of the receiving antenna 62 by means of conductors 66 and 67 respectively.

Referring again to FIG. 2, the supporting means for the illuminating means L also includes a pair of freely rotatable circular members or pulleys 68 and 69 which have peripheral grooves 68a and 69a and are mounted on the transverse rods 73 and 74 of frame F in transversely spaced apart relationship. The rotational axis of each of the pulleys 68 and 69 extends perpendicularly to the plane of the casing P in its vertically aligned position on the supporting rollers 28 and 29. In the illustrated embodiment, the circular members 68 and 69 are mounted on brackets 71 and 72, respectively, which are arranged for transverse sliding movement back and forth along rods 73 and 74 in the direction indicated by the double arrow U appearing on FIG. 2.

The sliding movement-of the brackets 71 and 72 is preferably produced by means of a threaded rod 75 which is arranged for rotation in threaded engagement with the brackets and is provided at one end'with a hand crank 76. Thus, clockwise rotation of the rod 75 moves the sliding brackets 71 and 72 and the associated pulleys 68 and 69 inwardly so that grooves 68a and 69a of the pulleys receive and engage the upper portion of side edges 46 and 47 in the planer area 48 of the casing. The pulleys 68 and 69 thus provide lateral support at the top of the floating illuminating means while permitting the advance of the tubular fabric T over the casing P.

The oscillator also includes a tank or tuned circuit 101 comprised ofa coil 102 and a capacitor 103 in the which is mounted adjacent to and within 1 inch of the coil in a plane parallel to the coil axis. The capacitor 103 is connected at one end to the upper end of coil 102 and at its other end to one conductor of the shielded coaxial cable 91. Thelower end of the coil 102 is connected to the other conductor of the shielded coaxial cable 91 and to ground at 107 so as to provide a positive feedback signal to the control grid 96 of the amplifier tube 92.

The tank circuit is tuned to an output frequency for the transmission of a beam of high radio frequency energy from the antenna 77 and, to this end, the tube cathode 94 is tapped by means of conductor 106 to the tank coil 102 at 105, the second full turn of the coil from ground. The positive feedback signal from the tank coil ground 107 to the control grid 96 is obtained by means of a grounded conductor which is connected to the grid'96 through a capacitor 1 11 and a globar resistor 112. A supplemental conductor 108 and a blocking capacitor 109 are also connected between round and the control grid to prevent any negative feedback that could damage the tube.

The means for connecting the transmitter to the associated source of electrical power includes a transformer 113 having a primary winding 1 14 connected to the power conductors 87 and 88 and a pair of secondary windings 116 and 117. Means are provided for connecting the secondary windings 116 to the tube heater 93 and includes a conductor 118 which is connected between one side of the secondary windings 116 and the heater 93. The heater power circuit is completed by connecting the other heater terminal to the other side of the secondary winding 116 by conductor 115. Connected in parallel withthe heater power circuit by means of conductor 120 is a smoothing capacitor 119 for the heater 93.

Means are also provided for connecting the other secondary windings 117 to the amplifier tube 92 and tank circuit 101. More specifically, the secondary windings 117 are connected by means of conductors 121 and 122to a full wave bridge rectifier comprised of four diodes 123, 124, 125 and 126, preferably through a time delay relay means designated generally by the letter D. The diodes 123 to 126 are interconnected by conductors 127 and 128 and the bridge is grounded by means of conductor 129 between diodes 123 and 124. The connection between the bridge and conductor 122 is obtained through the timed delay relay means D by a conductor 130. 1

In the preferred circuit, the d.c. voltage output of the full wave bridge isapproximately 600 volts d.c. (positive) and the bridge output is connected to the amplifier tube 92 by conductor 131 through a current limiting resistor 132 and a radio frequency choke coil 133 which in turn is connected to the screen grid 97 by conductor 134 through resistor 136 and to the plate 99 by conductor through resistor 137 for biasing the grid and plate accordingly. The r.f. coil 133, as is wellknown, prevents feedback to the full wave bridge and a filter capacitor 138 is also provided and is connected between the conductor 131 and ground by conductor 139. In the specific embodiment described, the choke coil 133 consists of approximately 42 turns of 17 guage, varnish covered copper wire closely wound on a /2 inch diameter post. The output of tube 92 from plate 99 is conducted to the tank circuit by conductor 135 which is connected to the tank circuit by conductor 141 through capacitor 142.

The time delay relay means D includes a heater relay 143 connected by means of conductors 144 and 146 to power conductors 87 and 88, respectively, and by means of conductors 148 and 149 to an energizing relay 147 of the Potter and Brumfield type. The relay 147 is connected to the windings 117 and the bridge by conductors 122 and 130 as previously described. The heater relay 143 includes a heating element 151 and a switch 152 so that, upon the connection of the primary winding 114 to the source of power through conductors 87 and 88 by the closing of switch 89, power will be applied to the full wave bridge through relay 147 by the heating and closing of switch 152 by means of heater 151 in relay 147. Upon closing switch 89, the tube heater 93 is also energized through secondary windings In the operation of the invention, with the tubular fabric advancing through the frame F as described above, power is supplied to the transmitter by closing switch 89 and the amplifier heater 93 begins to heat up with the application of approximately 6 volts of ac power from windings 116. Upon actuation of the time delay relay means D, power is supplied to the d.c. full wave bridge through the transformer secondary windings 117 to provide a d.c. output of approximately 600 volts for biasing the grids on the tube 92, the resulting outputof the tube 92 from the plate 99 being conducted to the tank circuit 101. The oscillator then becomes operative and the oscillations are sustained by positive feedback from the tank circuit 101 to the control grid 96 of tube 92.

A signal of predetermined frequency, approximately 30 megacycles in the preferred embodiment, is then transmitted through the shielded cable 91 to the transmitting antenna 77 where the signal is heaved to the receiving antenna 62 on the, casing P. Th'e'transmitting antenna for this frequency is preferably constructed as a directional coil consisting of four turns of A: inch copper tubing wound on a diameter of 1% inches witha inch spacing between adjacent coils. From the antenna 1 62, radio frequency energy is supplied to the copper strips 64 and 65 for ionization of the gas within the fluorescent tubes 61, thereby illuminating the tubes and providing a source of light from inside the fabric tube T to facilitate visual observation of the fabric by theinspector. It should be understood that the position of the tap 105 on the tank coil 102 is selected in accordance with the feedback signal desired and for purposes of matching impedance and determining the frequency of the beam emitted from the transmitting antenna 77. It should also be understood'that the receiving antenna is tuned to a resonant frequency so as to resonate at the transmitting frequency for maximum efficiency.

The fabric tube T is advanced over the outer surface of the ple'xiglass shells S and S" by the rollers 28 and 29 while the entire casing structure P is floatingly supported in the position shown in FIGS. 1 and 2 by those rollers and by the upper level pulleys 68 and 69. The invention also contemplates the substitution of light casings having various widths to accommodate varying sizes of the fabric tube T, and the floating casing and related support structure permit easy and rapid interchanges of light casings of different sizes. Furthermore, the operable air gap between the transmitting and receiving antennas is such that the antenna 77 can be mounted out of the way in a position that does not interfere either with cloth movement or a change of light casings. If desired, a yardage counter 155, supported on the frame F by means of a bracket 156 for engagement with the advancing fabric T, may be provided for recording the length of fabric inspected.

While there has been described what at present is considered to be the preferred embodiment of the invention, it should be understood by those skilled in the art that various changes and modifications. may be made therein without departing from the scope of the invention. Thus, the detection of fabric imperfections may be automated through the use of photo-sensitive devices such as that described in prior art U.S. Pat. No. 3 ,065,6 1 5 the present invention providing illumination for a full 360 inspection whether visual or automated. In addition, the one-pass roll to 'roll transfer of cloth minimizes inspection and operator time. Another advantage is that both the cloth loading and unloading points are at a height convenient to the operator and minimizing required body motion.

It is possible, of course, to use various features of the Having thus described the invention, what is claimed is: Y

1. A tubular fabric illumination system comprising a frame having means for advancing tubular fabric of indeterminate length continuously through said frame;

illuminating means disposed within the. interior of said tubular fabric and including a light transmitting casing, a light sourceoperatively responsive to radio frequency energy mounted on said casing, a radio frequency receiving antenna mounted on said casing, and circuit means on said casing for conducting radio frequency energy from said receiving antenna to said light source;

means disposed exteriorly of said tubular fabric for supporting said. casing in a selected position .on said frame, said supporting means being arranged to permit the advance of said tubular fabric through said frame with said casing in said selected position; a radio frequency transmitter associated with said frame and including a transmitting antenna disposed in radiation impinging relationship with said receiving antenna; and means for connecting said transmitter to an associated source of electrical power to activate said transmitting antenna and transmit a beam of radio frequency energy to said receiving antenna for energizing said light source, thereby illuminating said tubular fabric from within to facilitate inspection of said tubular fabric as it advances over said casing.

2. An illumination system in accordance with claim 1 wherein said casing comprises 'a substantially rectangular panel member of rigid material having a top edge, a bottom edge and a pair of side edges, said panel member including a relatively thin upper portion, a relatively thin lower portion, and a bulbous intermediate portion having a pair of spaced-apart side walls defining an interior chamber wherein said light source is disposed; and wherein said supporting means is arranged to support said panel member in a substantially vertically extending position for sliding advance of said tubular fabric over the outer surface of said panel member and between said support means and a portion of said outer panel surface.

3. An illumination system in accordance with claim 2 wherein said receiving antenna is mounted on the upper portion of said panel member and wherein said transmitting antenna is mounted on said frame in adjacent relationship with said receiving antenna.

4. An illumination system in accordance with claim 3 wherein said supporting means includes a pair of horizontally aligned, transversely extending rollers arranged in parallel spaced-apart relationship so as to produce a nip for accommodating the bottom edge of the lower portion of said panel member and underlie said bulbous intermediate portion in supporting engagement therewith; and wherein said means for advancing said tubular fabric includes means for driving said rollers to advance said tubular fabric continuously over said panel member with said pair of rollers in continuous underlying and supporting engagement with said panel member and in continuous frictional advancing engagement with said. fabric.

5. An illumination system in accordance with claim 4 wherein said casing supporting means also includes a pair 'of freely rotatable circular members each having a peripheral groove and mounted on said frame in transverse, spaced-apart relationship, each of said circular members having its rotational axis extending perpendicularly to the plane of said panel member as supported vertically on said pair of horizontal rollers; and means for adjustably moving said circular members transversely on said frame into and out of a position where one member receives a portion of one side edge and the other member receives a portion of the opposing side edge of said panel within said peripheral grooves thereby laterally supporting said panel member with said tubular fabric therebetween, permitting the advance of said tubular fabric with said illuminated casing floatingly supported therein at a fixed position in relation to said frame.

6. An illumination system in accordance with claim 3 wherein said light source comprises a plurality of ionizable, gas-containing tubes arranged in uniform, spaced-apart relationship.

7. An illumination system in accordance with claim 6 wherein only the side walls of the intermediate portion of said panel member are formed of lighttransmitting material.

8. An illumination system in accordance with claim 3 wherein said casing circuit means includes at least one elongated strip of conductive material mounted on said panel member within the interior of said panel chamber in overlying radiation impinging relationship with said plurality of tubes, and at least one conductor for connecting said receiving antenna to said conductive strip.

9. An illumination system in accordance with claim 3 wherein said radio frequency transmitter comprises 'an oscillator including a tank circuit and an amplifier,

said tank circuit being tuned for an output of a selected transmitting frequency, and means for connecting said tank circuit to said transmitting antenna; and wherein said means for connecting said transmitter to said associated source of electrical power comprises a transformer having a primary winding and a pair of secondary windings, means for connecting said primary winding to said associated source of electrical power, means for connecting one of said secondary windings to the heater component of said amplifier and means including a full wave rectifier bridge and a radio frequency choke'for connecting the other of said secondary windings to the oscillating components of said am plifier and said tank circuit.

10. An illumination system in accordance with claim 9 wherein said tank circuit includes an inductancecapacitance coupling'between a tank coil of copper tubing and an adjacent capacitor plate means insulated from ground, and wherein said rectifier bridge is connected to said secondary transformer windings through a time delayed relay means for interconnecting said secondary winding to said tank circuit and said amplifier after a predetermined time interval subsequent to the operation of said connecting means to the heater component of said amplifier. 

1. A tubular fabric illumination system comprising a frame having means for advancing tubular fabric of indeterminate length continuously through said frame; illuminating means disposed within the interior of said tubular fabric and including a light transmitting casing, a light source operatively responsive to radio frequency energy mounted on said casing, a radio frequency receiving antenna mounted on said casing, and circuit means on said casing for conducting radio frequency energy from said receiving antenna to said light source; means disposed exteriorly of said tubular fabric for supporting said casing in a selected position on said frame, said supporting means being arranged to permit the advance of said tubular fabric through said frame with said casing in said sElected position; a radio frequency transmitter associated with said frame and including a transmitting antenna disposed in radiation impinging relationship with said receiving antenna; and means for connecting said transmitter to an associated source of electrical power to activate said transmitting antenna and transmit a beam of radio frequency energy to said receiving antenna for energizing said light source, thereby illuminating said tubular fabric from within to facilitate inspection of said tubular fabric as it advances over said casing.
 2. An illumination system in accordance with claim 1 wherein said casing comprises a substantially rectangular panel member of rigid material having a top edge, a bottom edge and a pair of side edges, said panel member including a relatively thin upper portion, a relatively thin lower portion, and a bulbous intermediate portion having a pair of spaced-apart side walls defining an interior chamber wherein said light source is disposed; and wherein said supporting means is arranged to support said panel member in a substantially vertically extending position for sliding advance of said tubular fabric over the outer surface of said panel member and between said support means and a portion of said outer panel surface.
 3. An illumination system in accordance with claim 2 wherein said receiving antenna is mounted on the upper portion of said panel member and wherein said transmitting antenna is mounted on said frame in adjacent relationship with said receiving antenna.
 4. An illumination system in accordance with claim 3 wherein said supporting means includes a pair of horizontally aligned, transversely extending rollers arranged in parallel spaced-apart relationship so as to produce a nip for accommodating the bottom edge of the lower portion of said panel member and underlie said bulbous intermediate portion in supporting engagement therewith; and wherein said means for advancing said tubular fabric includes means for driving said rollers to advance said tubular fabric continuously over said panel member with said pair of rollers in continuous underlying and supporting engagement with said panel member and in continuous frictional advancing engagement with said fabric.
 5. An illumination system in accordance with claim 4 wherein said casing supporting means also includes a pair of freely rotatable circular members each having a peripheral groove and mounted on said frame in transverse, spaced-apart relationship, each of said circular members having its rotational axis extending perpendicularly to the plane of said panel member as supported vertically on said pair of horizontal rollers; and means for adjustably moving said circular members transversely on said frame into and out of a position where one member receives a portion of one side edge and the other member receives a portion of the opposing side edge of said panel within said peripheral grooves thereby laterally supporting said panel member with said tubular fabric therebetween, permitting the advance of said tubular fabric with said illuminated casing floatingly supported therein at a fixed position in relation to said frame.
 6. An illumination system in accordance with claim 3 wherein said light source comprises a plurality of ionizable, gas-containing tubes arranged in uniform, spaced-apart relationship.
 7. An illumination system in accordance with claim 6 wherein only the side walls of the intermediate portion of said panel member are formed of light-transmitting material.
 8. An illumination system in accordance with claim 3 wherein said casing circuit means includes at least one elongated strip of conductive material mounted on said panel member within the interior of said panel chamber in overlying radiation impinging relationship with said plurality of tubes, and at least one conductor for connecting said receiving antenna to said conductive strip.
 9. An illumination system in accordance with claim 3 wherein said radio frequency transmitter comprises An oscillator including a tank circuit and an amplifier, said tank circuit being tuned for an output of a selected transmitting frequency, and means for connecting said tank circuit to said transmitting antenna; and wherein said means for connecting said transmitter to said associated source of electrical power comprises a transformer having a primary winding and a pair of secondary windings, means for connecting said primary winding to said associated source of electrical power, means for connecting one of said secondary windings to the heater component of said amplifier and means including a full wave rectifier bridge and a radio frequency choke for connecting the other of said secondary windings to the oscillating components of said amplifier and said tank circuit.
 10. An illumination system in accordance with claim 9 wherein said tank circuit includes an inductance-capacitance coupling between a tank coil of copper tubing and an adjacent capacitor plate means insulated from ground, and wherein said rectifier bridge is connected to said secondary transformer windings through a time delayed relay means for interconnecting said secondary winding to said tank circuit and said amplifier after a predetermined time interval subsequent to the operation of said connecting means to the heater component of said amplifier. 